Long before Game Of Thrones began offing its lead characters with gleeful abandon, Spooks was blazing a trail for on-screen terminations. Often with actual blazes. Huge, remotely detonated ones. Suddenly, for the first time on a major BBC drama, no-one was safe. Neither, in some controversial cases, were they quite who they seemed…

Featherstone: Before the final episode, I tallied the number of lead characters we’d killed off. I think it was 17.

Macfadyen: The deep-fat fryer was the thing that grabbed everyone. Killing off Lisa Faulkner was a really good dramatic move.

“People still ask if I’ve been put off deep-fat fryers. I’ll walk into a kitchen and people will say, ‘Whooah! Keep her away from the fryer.’”

Lisa Faulkner

Heggessey: We wanted to do something that would grab the audience by the scruff of the neck.

Faulkner: People still ask if I’ve been put off deep-fat fryers. I’ll walk into a kitchen and people will say, “Whooah! Keep her away from the fryer.”

Featherstone: David had written this great idea for the final episode of the first season – it was going to be episode 13 in the development phase – and I just said, “What’s the best story we’ve got?” and it was that one. “If we bring that story forward, won’t that scare the pants off everyone?” Lisa was probably our biggest name at that point. We used that history she had with the audience.

Faulkner: I remember my neighbour saying, “God, you must have been so gutted.” I asked why and they said, “Well, did you know that was going to happen?” I said, “Yeah! It wasn’t like I’d been a really naughty girl in the first episode and they decided to get rid of me.” I’ve had to explain it to people because they’re so funny about it.

Nalluri: We cast her because she was the nation’s sweetheart, and we built her up as the overt love interest in the office. Then they went off on their undercover thing and she got deep-fat fried. (Laughs)

Faulkner: The chip fat was a mixture of tea and oil, and dry ice to make it look hot.

Nalluri: There was a bloke with a very long straw blowing into it!

Macfadyen: I just remember being on the floor shouting a lot.

Faulkner: My hair and the side of my face were really oily and wet. I look back and think, “Oh yeah, we were in that funny kitchen and my hand went in and then I died!” My family weren’t that bothered. My dad was like, “Oh yeah, you’ll do something else.” He's much more impressed by my cooking.

Featherstone: The scene gave us confidence for the future deaths. It became defining for the series. All bets were off.

Faulkner: I was shooting something for the BBC last Friday and one of the cameramen came up to talk to me about it. I thought, “This is crazy!”

Featherstone: I loved David Oyelowo’s death where he has the gun to his head and tells the terrorist to fuck off. Ruth’s too.

Walker: David’s death was the point were I thought, “Okay, this is great telly.” I had someone grab my hand on the Northern Line and start sobbing. I said, “I know, I know… but what an amazing exit!”

“The actors would get the script and think, ‘Am I going to make it to the end or will I be out of work next week?’”

Peter Firth

Firth: No-one had killed their heroes before and it was enormously powerful. Now it’s become standard practice.

Macfadyen: When Tom swims into the North Sea, I thought, “Well, that’s the end of him.” I’d only signed on for two seasons but I met Jane Featherstone and she sold me the idea of coming back for another couple of episodes.

Featherstone: Tom survived because he was the most resilient, clever, strong individual. (Laughs)

Macfadyen: We filmed that scene in Suffolk by a big nuclear power station and I had a bit of a hangover, so it was quite nice to get in the sea. How did Tom survive? I think he just used his genius spy-ness to hold his breath and float down the coastline. He was also in the swimming team at school and was first in his class at MI5 for holding his breath!

Firth: The actors would get the script and think, “Am I going to make it to the end or will I be out of work next week?” But Jane reassured me that they needed an anchorman, so I never thought Harry would die.

Penry-Jones: Adam’s death scene was incredible, like a bomb had gone off in the middle of London. The public were quite shocked when this huge mushroom cloud went up in the middle of Finsbury Square.

Featherstone: To do a massive explosion like that on a TV budget in the middle of town was pretty difficult.

Penry-Jones: I was watching from a safe distance!

Norris: I’ve never seen my death scene (Ros is killed by a bomb in season eight). I don’t know why, I just haven’t. I’d like to – maybe I will now! I put a lot into it.

Armitage: Fans didn’t like [the Lucas North/John Bateman twist]. They were very upset about that turnaround. I feel like they felt like the rug was being pulled out from under their feet. But I remember sitting down with (producer) Andrew Woodhead before we went into series nine and he said, “We’ve got this crazy idea for the character, what do you think?” and I said, “Yeah, do it!”

Vincent: In retrospect, we could have handled it better. When you pull the rug on fans over who a character is, you have to be prepared for people to be unhappy. That’s fair enough.

Featherstone: Occasionally we had to say, “This person is a really nasty piece of work”, which meant that you couldn’t necessarily trust everyone you met in the future. Spooks has always been a grey world.

Firth: The original script described a shot of Lucas North falling off one of the very tallest buildings in the city. It was terrifying, but that didn’t happen.

Armitage: I was always living with the hope that he hadn’t died (laughs). He could be out there, trying to infiltrate the CIA.

Brackley: You never saw the body.

Vincent: Well, you see a hand. Let’s just say it’s classified.

Featherstone: I felt very strongly about Ruth dying, and had many arguments with Sam [Vincent] and Jon [Brackley], but we couldn’t have Harry and Ruth walking off into the sunset together. It wouldn’t be true to the show.

Vincent: There was a very long conversation about whether it was too cruel on the audience. There are still a lot of people out there who are very unhappy and understandably. But Spooks was a very harsh world where people weren’t always rewarded.

Walker: The script came through and when the producer rang me I knew I was in trouble. I read it and I said, “Oh my God, you’ve killed me!” I couldn’t believe it. Part of me wanted to make it to the end, but it was absolutely the right thing to do.

Penry-Jones: I found [the show] very hard to watch as a punter once I’d left. It was a little painful. And now they’ve made a bloody movie!

Agutter: Where’s Tessa now? She’s probably in Paris running an illegal brothel and gathering a huge amount of information.

Macfadyen: I think Tom Quinn’s making a lot of money in one of those private security companies, floating around the world. Or he’s running a camping shop in the Brecon Beacons. He could be a swimming teacher!